Question

sin 75° вычислите
cos 15°

Answer 1

$cos15 = cosdfrac{30}{2} = sqrt{dfrac{1 + cos30}{2}} = sqrt{dfrac{1 + dfrac{sqrt{3} }{2} }{2} } = sqrt{dfrac{1 + sqrt{3} }{4}}  = dfrac{sqrt{1 + sqrt{3} } }{2}$

$sin75 = cos(90 - 75) = cos15$

Ответ: sin75° = cos15° = √(1 + √3)/2